The German Patent Disclosure Document 39 00 663 shows a cross cutting device as part of a folding machine where a web is partially cut by a first cutting device containing a cutting blade roller and a counter cylinder. The cutting blade is formed with breaks so that it leaves uncut sections in the cutting line. Pairs of pull rollers are provided on both sides of the cutting device. The partially cut web is then guided over a folding cylinder where it is cut completely while being partially wrapped around the cylinder and while being guided by belts. For this purpose, the folding cylinder, containing counter blade strips, is arranged with a cutting blade roller that also is equipped with a cutting blade which has breaks in it. These breaks are laterally offset from the breaks in the blade of the first cutting device so that the partially cut web is completely cut. The belts used for guiding the partially cut web are guided through the breaks in the blades. It is also possible to equip both cutting blade rollers with perforating blades having the same kind of breaks and to use the device for cross perforating.
The disadvantage of this system is that the partially cut web is not positively guided until it enters the area between the folding cylinder and the belts. This can cause web stretching that may lead to an offset of the two partial cuts causing the cut not to be straight and clean. Because the web stretching varies, the lengthwise offset of the cuts needs constant readjustment and, therefore, cannot be practically eliminated. Furthermore, the web can tear as a result of the partially cut web having no positive guidance. Also, a non-guided multilayer partially cut web folded lengthwise by a folding triangle, may form a bubble. Finally, the cross cutting devices, each containing two cutting blade rollers and counter cylinders as well as two pairs of pull rollers, are expensive to produce.